The present invention relates generally to a method and system for remediating contaminated soil and groundwater, and more particularly to a method and system for exposing contaminated groundwater to a re active medium suspended as a slurry throughout a reaction chamber.
There exists a variety of systems and methods employed for remediation of contaminated soil and groundwater. The following patents disclose some specific examples of soil and groundwater remediation systems that are known in the prior art. Each of these U.S. Patents is herein incorporated by reference for its supporting teachings.
U.S. Pat. No. 6,007,274 to Suthersan discloses a method and system for removing contaminants from the phreatic zone, also known as the saturation zone, or groundwater. The technique involves gas sparging and oxidation while increasing the surface area for mass transfer by the placing of packing balls into the eductor tube. The system is comprised of a means for supplying gas/ozone mixture to the lower extent of a well which induces a flow of groundwater and gas bubbles up the well. The system contains a conduit within the well, which extends below the water table. The conduit has a lower fluid-permeable section which is located below the water table and an upper fluid-permeable section which is adjacent the water table.
U.S. Pat. No. 5,967,230 to Cooper et al. discloses a remediation treatment that creates environmentally neutral species from hydrocarbon contaminants. A catalyst is injected into the site and is permitted to diffuse through the site. An oxidizing agent is then introduced into the site to release a free radical in a Fenton-type reaction. The compounds react to release a free radical, which acts upon the contaminants to form environmentally neutral species. Diffusion of both compounds is aided by turbulence induced in the groundwater. Reaction vapors are collected above ground, filtered, and vented to the atmosphere.
U.S. Pat. No. 5,879,108 to Haddad discloses an in situ air sparging/soil vapor extraction apparatus that includes first, second and third concentrically arranged pipes disposed in a single bore hole.
U.S. Pat. No. 5,855,775 to Kerfoot discloses an apparatus for active in situ multi-element gas sparging for bioremediation or physico-chemical degradation for removal of contaminants in a soil formation containing a subsurface groundwater aquifer or a substantially wet unsaturated zone.
U.S. Pat. No. 5,803,174 to Gilmore, et al. discloses a method and apparatus for the remediation of contaminated soil and groundwater wherein a reactive pack material is added to the annular fill material utilized in standard well construction techniques.
U.S. Pat. No. 5,620,593 to Stagner discloses an in-well system for simultaneously treating and extracting groundwater by injecting compressed gas through the groundwater in multiple successive stages as it is pumped out of a well. The process is usable for in-well aeration stripping of Volatile Organic Compounds from groundwater or for other applications in which it is desirable to pass compressed gas through groundwater to alter the physical, chemical, or radiological properties of the groundwater prior to its discharge from the well.
U.S. Pat. Nos. 5,611,642 and 5,525,008 to Wilson disclose a method and apparatus for in-situ treatment of soil and groundwater contaminated with organic pollutants. The process involves defining the nature and extent of the contamination; determining the hydrology and geology of the contaminated area; determining the volume and concentration of a reactive solution required to effect treatment of the contaminated area; injecting the reactive solution into one or more injectors that are inserted into the ground, sealed and positioned so as to assure flow of the reactive solution through the contaminated area; allowing the reactive solution to flow through the contaminated area thereby reacting chemically with the contaminants contained within the contaminated area; and determining when the treatment is complete by monitoring by-products of the chemical reaction. Preferably, the reactive solution is an aqueous solution of hydrogen peroxide and metallic salts.
U.S. Pat. No. 5,380,126 to Bernhardt discloses a device for rinsing contaminants from ground wherein groundwater is received in a well shaft through lower perforations, pumped up the well shaft, and out to upper ground regions through upper perforations, so that it can circulate back down to the groundwater level, thus flushing contaminants from the upper ground regions. A filter or cleaning device may be placed in the circulation path to remove contaminants.
U.S. Pat. No. 5,318,698 to Bernhardt discloses an arrangement for cleaning contaminated groundwater and a ground region through which it flows comprising a shaft extending to a region of groundwater to be cleaned, the shaft having a shaft wall with two water permeable wall regions located above and below a groundwater level so that a separating region is formed in the shaft between the water permeable regions under the groundwater level, a through going passage extending through the separating region and ending above the groundwater level in the shaft, a filter arranged in the shaft, and a circulating pump arranged in the shaft so that the through going passage forms a part of a flow path.
U.S. Pat. No. 5,286,141 to Vigneri discloses a method for remediating a hydrocarbon-contaminated region of a subterranean body of groundwater to destroy or reduce the initial concentration levels of hydrocarbon contaminants.
U.S. Pat. No. 5,180,503 to Gorelick, et al. discloses an in-situ system for removing volatile organic compounds (VOCs) from groundwater. The technique includes gas-lift pumping and in-situ vapor stripping.
As the foregoing references indicate, a common practice in soil and groundwater remediation is to introduce a reactive component into a contaminated area. The reactive component will then either physically remove the contaminant (e.g. it will be carried out in bubbles), or chemically react with the contaminant. In either case, the net result is the removal of the contaminants from the area.
A key consideration in groundwater remediation systems is the amount of time the system must operate in order to complete remediation. The longer a remediation system needs to operate, the greater the expense. Two key factors in determining operation time are 1) the effectiveness of the reactive component, and 2) the exposure the groundwater has to the reactive component. Therefore, a need exists for a groundwater remediation system that utilizes a more effective reactive component, and that can better expose the groundwater to the reactive components, thus requiring less operation time, and hence less expense.
It is therefore a feature of the present invention to provide a soil and groundwater remediation system and method that more effectively forces contact between contaminants in groundwater and a reactive medium. The method allows for improved reaction rates by suspending reactive particles within the fluid being treated. Improved reaction rates allow for less operation time, and hence less expense.
The present invention relates generally to a method and system for remediating contaminated soil and groundwater, and more particularly to a method and system for exposing contaminated groundwater to a reactive medium suspended as a slurry throughout a reaction chamber.
Specifically, the present invention is a liquid remediation system. The system includes a reaction chamber that has an inlet in communication with a source of liquid. A pump directs the liquid through the reaction chamber. A reactive medium that is dispersed throughout the reaction chamber chemically reacts with a contaminant. The liquid is directed back to the source from the reaction chamber, through at least one discharge loop, after the liquid has undergone a level of remediation.
The reaction chamber may optionally include an upper reaction chamber portion and a lower reaction chamber portion. The upper reaction chamber may form a horizontal extension that is substantially perpendicular to the lower reaction chamber, and may further include a vertical portion that is perpendicular to the horizontal extension. The vertical portion is in communication with the horizontal extension at an end of the horizontal extension opposite the lower reaction chamber opening.
In one embodiment, the upper reaction chamber comprises a chamber extension, a conduit in communication with the lower reaction chamber and extending into the chamber extension, and a plurality of openings in a bottom side of the conduit for initially directing the liquid in a downward direction inside the chamber extension.
Other optional features of the present invention include at least one recirculation pipe having one end in communication with the reaction chamber, and another end proximate to the inlet. It is also noted that the pump may include a discharge portion that is equipped with a slurry suspending nozzle.
Also disclosed in the present invention is a method of remediating a liquid. A reaction chamber is provided that includes an inlet that is in communication with a source of liquid. The liquid is directed through the reaction chamber by a pump. A reactive medium, that is dispersed throughout the reaction chamber, is chemically reacted with a contaminant in the liquid. Once the liquid has undergone a level of remediation, it is directed back to the source from the reaction chamber through at least one discharge loop.
There has thus been outlined, rather broadly, the more important features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. Other features of the present invention will become clearer from the following detailed description of the invention, taken with the accompanying drawings and claims, or may be learned by the practice of the invention.